Pulverized coal burners for partial oxidation of pulverized fuels, comprising a cylindrical water-cooled housing and internal coaxially disposed annuli for supplying the pulverized fuel and the oxidant, are well known.
Located in the center of the burner is a further small gas/oxygen burner which serves as an igniter or pilot burner and is equipped with an optical flame monitoring device and a high-voltage ignition device. It is used for starting up the abovementioned pulverized coal burner, as disclosed in the patent documents DE 271038 A3 and DE 4306980 C2.
The pulverized fuel is supplied outside and inside the burner through one or more tubes. Inside the burner, the supply tube(s) is (are) run to the burner outlet in such a way that they perform at least one complete rotation about the axis and then end set tangentially adjacent to the burner outlet. At the end of the pulverized fuel tube(s) the pulverized fuel dust enters a cylindrical annulus in a tangential manner.
At the transition from the tube surface area to the annulus there is an abrupt increase in area and therefore a reduction in the pulverized fuel dust velocity.
Although increasing the number of pulverized fuel tubes inside the annulus can reduce the areal discontinuity, it cannot eliminate it.
This results in an uneven distribution of the pulverized fuel stream inside the annulus, which can cause asymmetrical flame spread with unilateral stressing of the reaction chamber.
The known burner has the following disadvantages:                1. complicated design of the tubes inside the cylindrical annulus in the burner        2. after the pulverized coal dust outlet there is an unavoidable areal discontinuity, thereby reducing the dust velocity        3. this areal discontinuity causes the downstream annulus to be unevenly filled with pulverized coal dust, resulting in differential mixing with the oxidant.        